If you're traveling somewhere where it rains a lot (AKA the Pacific Northwest), then you should check out the DaKine Crew Duffle 90L Bag. With it's 600D Waterprrof PU Polyester your stuff will be able to stay dry even in the wettest conditions.
600D Waterproof PU Polyester
YKK waterproof zippered side and end pockets
U-shaped opening for easy access
Stowable padded shoulder straps
Padded shoulder strap